Skoglund et al. (2015) in a new manuscript attempt to resolve the emergence of modern canids using the genome of an ancient wolf from the Taimyr peninsula in Siberia to suggest a much older divergence date (>35,000 ybp, consistent with carbon dating estimates). The authors (a) construct an mtDNA phylogeny which suggests that the Taimyr wolf comprises a distinct lineage from all modern dog lineages, (b) estimate divergence time between modern dogs, and the Taimyr wolf using D statistics (also called the ABBA-BABA statistics – see Patterson et al. (2012)) to be consistent with the ~35,000 ybp carbon-dating estimate by using a slower mutation rate, (c) estimate approximately 3.5% (1.4% – 27.3%) derived ancestry in modern canids from Greenland, suggesting recent divergence of wolves and modern canids from the Taimyr wolf’s lineage.

…we find that the ancestry of present-day dog breeds descends from more than a single domestication event, since high-latitude dog breeds such as the Siberian Husky and Greenland Sledge Dogs can trace part of their ancestry to the now-extinct Taimyr wolf lineage. This introgression could have provided early dogs in high latitudes with phenotypic variation beneficial for adaptation to a new challenging environment.

In another interesting find, Xue et al. (2015) report that the 16s rRNA gene-based profile of fecal microbiota of the strictly bamboo-eating giant panda (Ailuropoda melanoleuca) indicates a surprisingly ‘carnivorous’ microbiome (Enterobacteriacae, and Streptococcus), as against surmised microbiota that are seen in other herbivores (Clostridiales, Fibrobacterales, etc).

Using 121 fecal samples from adults, and cubs, bacterial 16s rRNA genes were sequenced and analyzed to study the compositional variation of microbiota in the giant panda. Findings suggest (a) relative abundance of Streptococcus, and Escherichia across all samples, (b) drastic seasonal and age-related variation with significantly reduced diversity in late autumnal samples, and (c) a comparison of microbiome diversity using a PCoA indicate similarities in variation (clustering) of fecal microbiomes of the giant panda, and other carnivores.

Unlike other mammalian species that have evolved gut microbiota (and also digestive system anatomies) optimized for their specific diets, the aberrant coevolution of the giant panda, its dietary preferences, and its gut microbiota remains enigmatic.

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About Arun Sethuraman

I am a computational biologist, and I build statistical models and tools for population genetics. I am particularly interested in studying the dynamics of structured populations, genetic admixture, and ancestral demography.